Review: ALO Audio CDM – Heartwarming

Disclaimer: First of all I’d like to thank Ken and Caleb for sending me a CDM unit. Nathan actually sent me his CDM unit all the way from Japan as well, which allowed me to A/B test the stock CDM vs the tubes ALO sent me for the Tube Rolling article. This separate article will be published next week.

A few weeks ago Nathan already reviewed the Continental Dual Mono here on HFN and he absolutely loved it. That, luckily for me, also means I don’t have to go into all the technical details, looks, usability, etc. What I will do is:

  1. Tell you how I think it sounds,
  2. Explain how it performs versus the Chord Hugo
  3. Describe how the ALO Audio CDM reacts to tube rolling.

If you haven’t read Nathans thorough review yet, I advise you to do so before you start reading here.

The Continental Dual Mono

ALO Audio doesn’t put a product on the market just to have “something new” (ok, maybe they did with the “The Key”) and they’ve actually been working on the CDM for about two years. That does mean things kind of got quiet around them but like Nathan said: The CDM put them right back on the map. ALO has been working on the CDM together with Vinnie Rossi and if you know who that is you just know it most likely will sound good. He, amongst other, is the guy behind the Red Wine Audio mods we reviewed here before.

If you have ever listened to the ALO Studio Six you most likely will remember that for a very long time. The Studio Six is really big though. If I do get such a beautiful amplifier, I want it to be in the middle of my living room for everyone to see. Unfortunately my cat and my fiancée don’t agree and so all my tube amps are stored in my office upstairs. If only a mini Studio Six existed. That’s probably exactly what ALO was thinking as well seeing the portable CDM was developed with the S6 in mind. Can it be more perfect? The Continental Dual Mono is a “tube/SS hybrid” amplifier.  It delivers the low output impedance, tight bass and sonic precision of a solid-stage amp, but with the added midrange richness, expanded soundstage and spaciousness of a tube amp.

If you’ve seen the pictures I post on FB and Instagram, you know I regularly carry around a double or triple stacked portable rig. When I discovered the excellent Chord Hugo you could see me walking around rocking that and now there’s the ALO CDM: a portable DAC/AMP combo on tubes. Can it get any better? That doesn’t mean I don’t use the Hugo anymore, I actually still use it on a daily basis but I’ll get back to that later. I know the Oregon guys are working on a leather carrying case like Hugo has and that should really help. For now, the CDM isn’t the easiest to carry around: it is about the size of an iPhone 6+, and it can kind of get hot when it’s being used as a DAC. At the same time more and more pictures are popping up of people using the CDM on the go, so it can be done for sure.

Tube flavored. Hmm

The Continental Dual Mono can be used as:

  • DAC only
  • AMP only

When used as DAC only, you can connect a different amplifier to the CDM using the dedicated 2Vrms Line Out on the back of the unit. The signal doesn’t pass the headphone amp section or the volume control. I have to admit I haven’t used the CDM as DAC only. Not that it’s a bad DAC but it to me isn’t the ultimate DAC either. ALO and Vinnie chose the Wolfson WM8741 (it’s located on the downside of the PCB) because it has exceptional signal to noise ratio and extended dynamic range. It also provides low noise, low distortion and superior linearity. The Wolfson chip also provides native high resolution DSD and PCM playback. I had to install some drivers for it to work correctly in Foobar, but everything was explained in a detailed way in the ALO CDM FAQ.

A few years ago I was a big fan of the Wolfson DACs but my tastes have evolved more to ESS Sabre chips lately. That being said, the sound signature of the WM8741 fits perfectly with the smooth sound of tubes. If you’re using the CDM as DAC you will notice the unit will get hot to the touch, it hasn’t bothered me at all but it is something to take into account in case you were planning on keeping it your pants’ pocket.

I used the CDM in amplifier only mode in two different setups. One where I hooked it up to the HUGO, which was being used as DAC, together with the Hifiman HE1000 as headphone. The combination is sublime. More on that in the part below. The other was when feeding the CDM through the Astell&Kern AK240 and that’s where it gets really interesting. When using the CDM’s amp you have a lot of possibilities: balanced in/balanced out, SE in/balanced out, balanced in/SE out, SE in/SE out. Each combination has its own sound, just like Nathan described. With some headphones/monitors I preferred the balanced in/out and with others I preferred the SE output. The beauty of the CDM is that it allows you to try them all and use the one you like most. They all sound really good. The difference often is the in the bass impact, detail level, spaciousness and sound stage.

Most of the time however, I used the CDM as a dedicated Amp/DAC unit at the office. You get desktop quality in a small package. Top quality sound at work, I ask for nothing more. The CDM drives all my headphones and earphones and it does so silently. When I use my sensitive monitors with the Cypher Labs Trio amp that also uses the 6111 (Thompson) tube, the hiss is audible. I’m not saying there isn’t any hiss with the CDM but it’s very limited, it’s more IEM friendly and that’s always a good thing. CDM also sounds more tube like than the Trio does, it has more detail and space but it goes for almost triple the price the Trio goes for as well.($599)

Sound continues on Page 2, and CDM gets compared to the HUGO. After the click HERE

4.7/5 - (10 votes)

Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.


  • Reply September 10, 2015


    Hi! Good article, thank you. So how does it perform against the older Alo PanAm? 🙂

  • Reply September 11, 2015


    Great stuff! Look forward to the tube rolling article.

    a) i know there are adaptors and stuff, but 2.5mm trrs balanced is still only with iriver A&K right?

    b) Just on the Hugo, the dac and amp output is the same signal. For technical accuracy we are really referring to adding colouration to the Hugo output when using an external amps, which may have pleasing results case-by-case.

    See comments section here:

  • Reply September 13, 2015

    Ted Tillholm

    Hi Liven, welcome back after your big summer.

    I was wondering if you can give a basic comparison between the CDM and HPA-01M?

    I’ve been looking at the Bakoon ever since your review came out, and now this new ALO product looks so good.

    • Reply September 13, 2015


      Hi Ted. Those are completely different units looking at design/technicalities and sound.
      The HPA-01M has the unique Satri current tech and it plays exceptional with Audeze planars. The CDM is a tube DAC/AMP and plays great with a whole lot more headphones.

      It depends on what you need. Do you need a DAC? Do you need it to work with non planars? CDM also is IEM friendly

      • Reply September 14, 2015

        Ted Tillholm

        Liven, I have planars but not Audeze, PM-2/AD. I already have a DAC, Solo-dB. I prefer the sound of my Continental v3 over my Pure II. Any comments on sound differences between the CDM vs. HPA-01M would be great.

        • Reply September 14, 2015


          It’s a tough one. CDM is smoother, wider sound stage and more layering. Bakoon is more power, great bass. the HPA-01M has a really unique sound with the Satri circuit, you really have to hear it for yourself.

          I do think the CDM would be the best one for you, it’s easier to use with other headphones while the Bakoon is really great for Audeze and Hifiman

          • Reply September 15, 2015

            Ted Tillholm

            This decision is not easy, thanks for your help.
            I wonder if Bakoon has a return policy, I really want to hear their amp.

  • Reply October 18, 2015


    Hey, how does the dac section of the CDM compare to the dac section of the theorem 720?

  • Reply January 9, 2017

    Griffin Cui

    This review is not accurate, the stock tubes do not drive CDM near its potential. The DAC of CDM with Mullard tubes almost sound as good as my McIntosh D150. The bass performance out of CDM with SE846 and Messdrop TH-X00 is awesome, anymore bass will give you a headache!

    • Reply January 24, 2017

      Benjamin Fong

      Griffin what Mullard tubes you referring ? I m very new to tube n cdm. Just bought it. Still trying to learn.

  • Reply January 14, 2017

    Benjamin Fong

    Can cdm handle beyerdynaic t1 well ?

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